When does a VW make sense?

Discussion in 'Volkswagen' started by JohnR, Feb 22, 2009.

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  1. Feb 22, 2009 #1

    JohnR

    JohnR

    JohnR

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    I'm building a full-size J-3 replica, and the numbers sure point to a VW conversion. However, I spoke with Great Plains, and the only way it would work well on a plane like this (lots of drag) is with a reduction drive.

    So there go any weight savings over a Continental A65, and the complexity of the redrive is an added headache. The reason a redrive is needed is to get enough torque for the prop to convert to thrust.

    I've run the numbers on a few engines, and nothing in the 65 HP family produces as much torque as a Cont. A65. The prices are good, it's simple and proven, and the weight is reasonable.

    My plane was designed around the Rotax 582, but I'm scared of 2-strokes. I looked hard at the Hirth engines, but they're expensive, and they're still 2-strokes (and still don't put out the torque of an A65).
     
  2. Feb 22, 2009 #2

    addaon

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    Personally, I'd go with an A65 or a Jab 2200. The Jab is lighter, more power, and more price.
     
  3. Feb 22, 2009 #3

    JohnR

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    I wish I could afford the Jab. I also like the 2300 RPM of the A65 vs. something like 3600 for the Jab. My ears will appreciate it!
     
  4. Feb 22, 2009 #4

    addaon

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    3300 for the Jab; but the Jab gives at least as much power if you cap it at 2500 rpm as the A65, at a lot less weight... I recall the A65 being around 200 lbs, no? That's the same weight as an IO-233 at close to twice the power.
     
  5. Feb 22, 2009 #5

    PTAirco

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    If you can find a cheap 65 hp Continental, I would go for it. I like VW's but once the conversion runs past $5000 or so, you might as well buy a used A-65 with maybe half its life remaining.
    Although when it comes to TBO, a VW would cost peanuts to re build compared to the Contintental.
     
  6. Feb 22, 2009 #6

    djschwartz

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    Another factor to consider: the A series Continentals have no provisions for any electrical system. If you want a starter or alternator you would need a C series Continental (C-75, C-85, C90, or O-200). The original equipment starters and generators that these came with were very heavy. Excellent lightweight starters and alternators are available for these engines. I have a Skytec starter on my O-200 powered Luscombe and am very happy with it. I also have a certified 35 amp alternator since it is a standard category aircraft. There are yet lighter and less expensive units available for experimentals.

    Also, the dry weight of the A-65 is 170 lbs. This does not include exhaust system. The dry weight of the O-200 is 215 lbs which includes the old, heavy accessories but not the exhaust system. With the lightweight electricals it should weigh a bit less than 200 lbs depending on which ones you choose. And for that you get 100 HP at an RPM that will result in good propellor efficiency at the speeds you will operate a J-3 replica.
     
  7. Feb 23, 2009 #7

    BBerson

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    A direct drive VW might work with a large low pitch prop. My Grob G109 has a direct drive 2000cc Limbach (VW) with a two position prop. In low pitch it will cruise about 70kts and 90kts in high pitch. If you are happy with 70kts, a large, direct drive fixed pitch prop might work if the plane is very light. (and the pilot also)
    VW is smoother than an A65 but less total thrust, I think.
    BB
     
  8. Feb 23, 2009 #8

    jumpinjan

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    If you put that VW & PSRU on your J-3 replica, it will leap off the ground. Our club member Gwen, put a Great Plains VW & reduction gear on her Fokker D8 and never regretted it.
    (I have heard the same response from other WWI replica builders that upgraded to the re-drive from a direct drive engine. Forget the A65 and everything else recommended)
    http://wrightpatrol.org/Gwen/4_Aug_07_ 018.jpg
    Jan

    [​IMG]
     
  9. Feb 23, 2009 #9

    wally

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    Hi,
    Looks like an engine and their reduction drive from Great Planes might be the way to go. At least I like it.

    You can buy a complete engine kit (you assemble) and a re-drive, all new stuff for about $4500. Or build your own engine up from whatever special piece parts GP sells, like a crank w/prop flange already on it, etc. and buy their re-drive. You might be under $3000, ready to fly with a little luck and work.

    A friend of mine just had his 85 Cont. overhauled on his Clipped Wing Cub. He said the final price was $12,000.!!!
    Granted about all they saved was his case but still...Dang!
    Best wishses,
    Wally
     
  10. Feb 23, 2009 #10

    Topaz

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    For me, it depends upon how long you intend to keep this airplane and what you expect your financial capabilities to be in the future. The VW is a solid, well-performing engine, as is the Conti. Don't be afraid of the redrive on the VW. GP's redrive seems to have a good record of service.

    The only technical reason to go with the VW that I can see is what DJSchwartz said: the VW will have full accessories for the price, but the Conti may not. Otherwise these are both very good engines.

    In the long run, though, if you intend to keep the airplane through at least one TBO cycle, the VW will save you thousands of dollars. Even on a top-end, the VW will be far less to have work done, and you'll be able to get most of the parts at any auto supplier.
     
  11. Feb 24, 2009 #11

    JohnR

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    Lots of good info here, thanks all.

    This idea sounds interesting:
    That's about J-3 speed anyway, and I don't want an electrical system. As for a "large low-pitch prop" maybe a three blade Warp Drive or Ivoprop in the wider blade models?
     
  12. Feb 24, 2009 #12

    JohnR

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    Ok, the answer is no.

    From Great Planes' website:

    [SIZE=+1]Great Plains engines (when driven off the pulley end) are for use with wooden propellers only. Metal or composite propellers are not allowed.[/SIZE]
     
  13. Feb 24, 2009 #13

    Grimace

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    Oh just go with a corvair motor and be done with it... ;-)
     
  14. Feb 24, 2009 #14

    gschuld

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    :roll: As I was reading the thread, I was thinking the exact same thing!


    [​IMG]
     
  15. Feb 24, 2009 #15

    JohnR

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    At 220#, I don't think so.
     
  16. Feb 24, 2009 #16

    Joe Kidd

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    You do have options for an engine aside from those mentioned. The newer BMW engines with redrive are lightweight powerhouses. Four cylinder Geo engines with a redrive are heavier but do a good job. Also if your looking at a 65 to 75 HP engine HKS has a beauty that comes with a redrive.
    I'm weighing my options based on an ever tightening budget so the two most cost effective options I've found to build are the 2180 VW and a 2700 Corvair. But, I'm still researching and looking around the area.
     
  17. Feb 25, 2009 #17

    macosxuser

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    An old C-75 or C-85 would probably be the easiest to find, and cheap. There was an O-200 core kicking around for $500 the other week in socal. Having RACED with these engines are Reno, I can tell you they are completely bulletproof, parts are easy to find still, and overhauls should run in the range of $5000-8000 depending on your level on involvement and whats wrong with them. The bottom ends usually last for oh, 4000 hours or 50 years, and the top end needs a refresh every 1500 hours or so.

    We spin them up to 4200+ RPM and 250°+ of oil temp for 15-25 hours (one season), then pull the jugs, look at it... hey looks good, put it back together and run another season...
     
  18. Feb 25, 2009 #18

    Topaz

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    While I would never argue against a certified engine for someone who wants one, part of the issue here is that $5,000-8,000 would buy you an complete brand-new VW-conversion engine and all-new accessories, instead of just an overhaul. The overhaul on the VW, even a major, will only be a fraction of the top-end overhaul price on the certified engine.

    Total-cost-over-life for a certified engine like this is orders of magnitude higher than a solid VW conversion that's likely to be just as reliable in actual service. Certified engines make sense for the higher-performance, more mission-critical end of light aircraft, but for the smaller, lighter, slower, simpler end of things, they really don't, IMHO.
     
  19. Feb 25, 2009 #19

    JohnR

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    Another aspect is availability - There always seem to be a handful of Continentals for sale, but you'll probably waste a bunch of time picking over duds before finding a good one. I've seen lots of A65s for sale between $1,800 and $3,000, and some for $6-7,000. A VW conversion is just a phone call away.
     
  20. Feb 25, 2009 #20

    orion

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    This is actually a rather important point and one that's often missed by those looking to do an auto conversion, and especially one that's based on the VW. While that Lyc or Cont will last you for quite some time, the VW conversions have on average a much shorter life. True, there are folks out there who get extended usage, some by quite a bit, but last I heard the average life of these small engines is in the range of about 200 hours. So you may have to figure the increased frequency of rebuild or maintenance into your cost numbers when comparing the auto alternatives and the certified engines.
     

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